Due to the development of communications systems, a wide range of wireless terminals have been introduced to consumers. Lastly, mobile communications systems have been employed the 3rd generation partnership project (3GPP) technologies, such as long term evolution (LTE) and LTE-Advanced. Such mobile communication systems are high-speed and high-capacity communications systems that may transmit various types of data, voice and data at a high speed. may
Such high-speed and high-capacity communications systems require technology for improving the capacity of a terminal using a small cell. In addition, in order to improve the capacity of a terminal using a small cell, it may require a technology enabling terminals for transmitting and receiving data by connecting a plurality of base stations together when the small cells are used. In this regard, there are many researches made for developing i) technology for dual connectivity (DC) that aggregates one or more cells controlled by two or more base stations and ii) technology for processing a large amount of data at a high speed by aggregating one or more cells and carrier aggregation (CA).
As described, there are many studied made for developing technologies for processing a large amount of data at a high speed by aggregating a plurality of cells through the dual connectivity (DC) or the carrier aggregation (CA). However, since uplink control information (e.g. channel state information) is transmitted and received through a single cell (e.g. a primary cell (PCell) or a primary secondary cell (PSCell)) for each base station, the load for uplink signals of cells transmitting the uplink control information increases with increases in the number of cells subjected to CA. This may cause a problem in terms of efficient data processing.